1. Field of the Invention
This invention relates to a closed alkaline wash water system for cleaning metal-working oil and scale from metal parts in the process of their manufacture and then cleaning the alkaline wash water of the metal-working oil and scale removed from the metal parts and reusing the wash water.
2. Description of the Prior Art
Prior to heat treating stamped, forged or machined metal parts, it is often necessary to remove accumulated metal-working oils. This is usually done with a wash or rinse using various alkaline detergent cleaning solutions, at a temperature of 180.degree.-200.degree.F. at a pH range of 9 to 13. Various commercial units, such as the Blakesley, the Ransehoff and the Combustion Engineering machines use either rotary drum, belt or dipping, with and without spray headers, to clean parts, i.e., chain links or side bars, pins, barrels, transmission sections, and the like. Spent alkaline cleaner contains approximately 10,000mg/l tightly emulsified oil at a pH 12. When added to other dilute high flow streams, a difficult waste water treatment problem is created. This oil and spent detergent wash water can be collected and treated conventionally by the use of equalization holding tanks, removal of free oil and settleable solids, acidification and removal of broken emulsion oils, chemical coagulation, sedimentation and/or flotation, neutralization (as required) and sludge disposal.
However, this approach requires production floor space and above daily normal operating talents such as determining daily chemical pretreatment (this varies from batch to batch) and proper sequential processing of batch flows, addition of chemicals, removal of separated solids, and laboratory analysis of discharged effluent samples. It also requires high capital cost in initial equipment.